Australasian Science: Australia's authority on science since 1938

Long-Term Toxicity of GM Maize

By Compiled by AusSMC

French research published in Food and Chemical Toxicology suggests that rats fed a diet containing a Roundup-tolerant genetically modified maize died more frequently and earlier than control groups. The study also suggests that females developed mammary tumours more often than and before controls.

“The current paper is far from convincing from a toxicological perspective. The study was based on 10 rats of each sex per treated group, and there was no consistency to any dose–response relationship, and much variability between the outcomes in the various groups. It was difficult to determine whether any effects on health or survival (if really present) were attributable to the GM maize, to the Roundup herbicide (glyphosate) or to neither. While the results were analysed using an unusual statistical technique, I felt that the authors substantially over-interpreted the findings.”

Professor Brian Priestly is Director of the Australian Centre for Human Health Risk Assessment at Monash University. He currently sit on the Gene Technology Technical Advisory Committee, and his comments do not represent the views of the Gene Technology regulator. He is also a Science Fellow of Food Standards Australia New Zealand, but is not a spokesperson for FSANZ on these issues.


“Contrary to the claims in the media releases, this is NOT the first long-term safety study into either Roundup or GM. There are more than 100 feeding studies on GM. Further, the European Commission, based on their own research on a wide range of theoretical health and environmental risks, at a cost of more than €300 million, found in 2010 that: “The main conclusion to be drawn from the efforts of more than 130 research projects, covering a period of more than 25 years of research, and involving more than 500 independent research groups, is that biotechnology, and in particular GMOs, are not per se more risky than e.g. conventional plant breeding technologies” (A Decade of EU-funded GMO Research 2001–2010, p.16).

Similar claims have been made by lead author Seralini in the past, and rejected by the European Food Safety Authority ( This paper itself has several errors, including gross statistical mistakes, as found in the previous EFSA review.

The World Health Organization (WHO) has stated: “GM foods currently available on the international market have passed risk assessments and are not likely to present risks for human health. In addition, no effects on human health have been shown as a result of the consumption of such foods by the general population” (”

Professor Rick Roush is the Dean of the Melbourne School of Land and Environment at the University of Melbourne.


“The first thing that leaps to my mind is why has nothing emerged from epidemiological studies in the countries where so much GM has been in the food chain for so long? If the effects are as big as purported, and if the work really is relevant to humans, why aren’t the North Americans dropping like flies? GM has been in the food chain for over a decade over there – and longevity continues to increase inexorably!

And if the effects are as big as claimed, why have none of the previous 100+ studies by reputable scientists, in refereed journals, noticed anything at all?

Finally, this was a study of one event with one gene. To then extrapolate to all genetically modified crops is absurd. Even if it eventuates that there is an issue with this one event, or even this one gene, there is no reason at all for other genes introduced using GM to carry the same burden of risk. GM is an adaptation of a natural process that occurs all the time all over the planet – it is “only” a technology, a technique. It is how it is used that is more important.

Generalisations about the risk of the technology per se are absurd.”

Professor Mark Tester is Professor of Plant Physiology at the Australian Centre for Plant Functional Genomics, University of Adelaide, and Director of the Australian Plant Phenomics Facility.